# Constants

Double-precision floating-point mathematical constants.

## Usage

```
var constants = require( '@stdlib/constants/float64' );
```

#### constants

Double-precision floating-point mathematical constants.

```
var c = constants;
// returns {...}
```

`APERY`

: Apéry's constant.`CATALAN`

: Catalan's constant.`CBRT_EPS`

: cube root of double-precision floating-point epsilon.`E`

: the mathematical constant*e*.`EPS`

: difference between one and the smallest value greater than one that can be represented as a double-precision floating-point number.`EULERGAMMA`

: the Euler-Mascheroni constant.`EXPONENT_BIAS`

: the bias of a double-precision floating-point number's exponent.`FOURTH_PI`

: one fourth times the mathematical constant π.`FOURTH_ROOT_EPS`

: fourth root of double-precision floating-point epsilon.`GAMMA_LANCZOS_G`

: arbitrary constant`g`

to be used in Lanczos approximation functions.`GLAISHER`

: Glaisher-Kinkelin constant.`HALF_LN2`

: one half times the natural logarithm of 2.`HALF_PI`

: one half times the mathematical constant π.`HIGH_WORD_EXPONENT_MASK`

: high word mask for the exponent of a double-precision floating-point number.`HIGH_WORD_SIGNIFICAND_MASK`

: high word mask for the significand of a double-precision floating-point number.`LN_HALF`

: natural logarithm of`1/2`

.`LN_PI`

: natural logarithm of the mathematical constant π.`LN_SQRT_TWO_PI`

: natural logarithm of the square root of 2π.`LN10`

: natural logarithm of`10`

.`LN_TWO_PI`

: natural logarithm of`2π`

.`LN2`

: natural logarithm of`2`

.`LOG10E`

: base 10 logarithm of the mathematical constant*e*.`LOG2E`

: base 2 logarithm of the mathematical constant*e*.`MAX_BASE10_EXPONENT_SUBNORMAL`

: the maximum base 10 exponent for a subnormal double-precision floating-point number.`MAX_BASE10_EXPONENT`

: the maximum base 10 exponent for a double-precision floating-point number.`MAX_BASE2_EXPONENT_SUBNORMAL`

: the maximum biased base 2 exponent for a subnormal double-precision floating-point number.`MAX_BASE2_EXPONENT`

: the maximum biased base 2 exponent for a double-precision floating-point number.`MAX_LN`

: natural logarithm of the maximum double-precision floating-point number.`MAX_SAFE_FIBONACCI`

: maximum safe Fibonacci number when stored in double-precision floating-point format.`MAX_SAFE_INTEGER`

: maximum safe double-precision floating-point integer.`MAX_SAFE_LUCAS`

: maximum safe Lucas number when stored in double-precision floating-point format.`MAX_SAFE_NTH_FIBONACCI`

: maximum safe nth Fibonacci number when stored in double-precision floating-point format.`MAX_SAFE_NTH_LUCAS`

: maximum safe nth Lucas number when stored in double-precision floating-point format.`MAX`

: maximum double-precision floating-point number.`MIN_BASE10_EXPONENT_SUBNORMAL`

: the minimum base 10 exponent for a subnormal double-precision floating-point number.`MIN_BASE10_EXPONENT`

: the minimum base 10 exponent for a normal double-precision floating-point number.`MIN_BASE2_EXPONENT_SUBNORMAL`

: the minimum biased base 2 exponent for a subnormal double-precision floating-point number.`MIN_BASE2_EXPONENT`

: the minimum biased base 2 exponent for a normal double-precision floating-point number.`MIN_LN`

: natural logarithm of the smallest**normalized**double-precision floating-point number.`MIN_SAFE_INTEGER`

: minimum safe double-precision floating-point integer.`NINF`

: double-precision floating-point negative infinity.`NUM_BYTES`

: size (in bytes) of a double-precision floating-point number.`PHI`

: golden ratio.`PI_SQUARED`

: π².`PI`

: the mathematical constant π.`PINF`

: double-precision floating-point positive infinity.`PRECISION`

: effective number of bits in the significand of a double-precision floating-point number.`SMALLEST_NORMAL`

: smallest positive**normalized**double-precision floating-point number.`SMALLEST_SUBNORMAL`

: smallest positive**denormalized**double-precision floating-point number.`SQRT_EPS`

: square root of double-precision floating-point epsilon.`SQRT_HALF_PI`

: square root of the mathematical constant π divided by 2.`SQRT_HALF`

: square root of`1/2`

.`SQRT_PHI`

: square root of the Golden ratio (φ).`SQRT_PI`

: square root of the mathematical constant π.`SQRT_THREE`

: square root of`3`

.`SQRT_TWO_PI`

: square root of the mathematical constant π times 2.`SQRT_TWO`

: square root of`2`

.`TWO_PI`

: the mathematical constant π times 2.

## Examples

```
var objectKeys = require( '@stdlib/utils/keys' );
var constants = require( '@stdlib/constants/float64' );
console.log( objectKeys( constants ) );
```